send suback 0x80 if subscribe authorization fails
replace async.parallel with async.map
Merge pull request #170 from mocheng/fix_124_169

send suback 0x80 if subscribe authorization fails
allow persistence.factory in options to be string
support case insenstive persistence string
1) refactor code; 2) fail with Error object instead of string
Merge pull request #171 from mocheng/fix_126

allow persistence.factory in options to be string
no storeInflightPackets when persistClient
Bumped browserify, mqtt and st dependencies.
Update offline packets with messageId === 0.

Closes #174.
Merge branch 'master' into fix_173
remove useless storeInflightPackets
use uuid for server level messageId
Merge pull request #175 from mocheng/fix_173

no storeInflightPackets when persistClient
generate unique id by shortid
Merge pull request #176 from mocheng/fix_172

use unique id for server level messageId
Removed node-uuid in favor of shortid.
pre-commit should be in devDependencies
Merge pull request #177 from mocheng/fix_package.json

pre-commit should be in devDependencies
Bumped v0.23.0. Updated HISTORY.md.